Entrance Rate Research Articles

Kinetics of transport of sodium chloride using supported liquid pertraction

In the present work, the removal of NaCl using the present type of supported liquid membrane technique has been investigated. A simple apparatus devised and constructed was used to conduct the experiments. Various factors that would affect the progress of transport were studied and these were initial concentration (Ci) of simulated seawater in donor phase (DP), presence of mobile carrier (MC) in the liquid membrane (LM), concentration of MC in LM, presence of sequestering agent (SA) in the receptor phase (RP), and speed of stirring. The volume ratio of DP to RP was kept constant at 2:1. Type (1,2 dichloroethane (DCE)) and thickness (2 mm) of LM were kept constant. Cellophane constituted the support for the LM. The most important findings emphasized the importance of the presence of a MC in the LM to enhance mass transfer through the LM and that an optimum concentration of MC existed. Also the importance of stirring in promoting mass transfer by minimizing the boundary layer intact to the cellophane support was elucidated. The best conditions arrived at were MC = 0.0538 mol/l (mol of dibenzo-18-crown-6/l of LM), SA = 0.0617 mol/l (mol of soluble starch/l of RP), slow stirring (100 rpm) of DP, and using DCE as LM. The mass transfer of NaCl was analyzed based on kinetic laws of two consecutive irreversible first-order reactions, and kinetic parameters (k1d, k2m, k2r, Rmmax, tmax, Jdmax, Jrmax) for the transport of NaCl were investigated. The values obtained demonstrate that the process is diffusion-controlled. Results indicate that the membrane entrance and exit rate constants (k1, k2) increase directly with Ci and inversely with quantity of SA.

Comparison of catch per unit effort among four minnow trap models in the three-spined stickleback (Gasterosteus aculeatus) fishery.

Minnow traps are commonly used in the stickleback (Gasterostidae) fishery, but the potential differences in catch per unit effort (CPUE) among different minnow trap models are little studied. We compared the CPUE of four different minnow trap models in field experiments conducted with three-spined sticklebacks (Gasterosteus aculeatus). Marked (up to 26 fold) differences in median CPUE among different trap models were observed. Metallic uncoated traps yielded the largest CPUE (2.8 fish/h), followed by metallic black nylon-coated traps (1.3 fish/h). Collapsible canvas traps yielded substantially lower CPUEs (black: 0.7 fish/h; red: 0.1 fish/h) than the metallic traps. Laboratory trials further revealed significant differences in escape probabilities among the different trap models. While the differences in escape probability can explain at least part of the differences in CPUE among the trap models (e.g. high escape rate and low CPUE in red canvas traps), discrepancies between model-specific CPUEs and escape rates suggests that variation in entrance rate also contributes to the differences in CPUE. In general, and in accordance with earlier data on nine-spined stickleback (Pungitius pungitius) trapping, the results suggest that uncoated metallic (Gee-type) traps are superior to the other commonly used minnow trap models in stickleback fisheries.

Inflow rate, a time-symmetric observable obeying fluctuation relations.

While entropy changes are the usual subject of fluctuation theorems, we seek fluctuation relations involving time-symmetric quantities, namely observables that do not change sign if the trajectories are observed backward in time. We find detailed and integral fluctuation relations for the (time-integrated) difference between entrance rate and escape rate in mesoscopic jump systems. Such inflow rate, which is even under time reversal, represents the discrete-state equivalent of the phase-space contraction rate. Indeed, it becomes minus the divergence of forces in the continuum limit to overdamped diffusion. This establishes a formal connection between reversible deterministic systems and irreversible stochastic ones, confirming that fluctuation theorems are largely independent of the details of the underling dynamics.

Bulk liquid pertraction of NaCl from aqueous solution using carrier-mediated transport

In the present work, removal of NaCl using the bulk liquid membrane (BLM) technique has been investigated, using a simple apparatus for conducting the experiments. Variables investigated were volume ratio of donor phase (DP) to receptor phase (RP), presence of sequestering agent (SA) in RP, type of organic liquid membrane (LM), quantity of mobile carrier (MC) in the LM. Stirring speed and volume of LM were kept constant at 100 rpm and 130 ml, respectively. The mass transfer of NaCl was analysed based on kinetic laws of two consecutive irreversible first-order reactions, and kinetic parameters (k1d, k2m, k2r, , tmax, , and ) for the transport of NaCl were investigated. The values obtained demonstrate that the process is diffusionally controlled. Results indicate that the membrane entrance and exit rate constants (k1, k2) increase with decreasing DP:RP ratio and with decrease in quantity of MC, and quantity of SA, and the presence of dichloroethane (DCE) is preferred to chloroform (CF) as LM.

Sustained Increased Entry of Medical Students into Surgical Careers: A Student-Led Approach

To determine whether a surgical interest group run entirely by preclinical students can influence medical students to enter general surgery residency programs. Matriculation rates into general surgery and affiliated subspecialties from Columbia University College of Physicians and Surgeons residency match lists were compared to National Residency Match Program data for all U.S. senior students from 2006 to 2014. The Columbia University College of Physicians and Surgeons. After establishing the interest group, entrance rates into general surgery programs tripled from the early 2000s to more than 12% of 2006 Columbia University College of Physicians and Surgeons graduates. After 8 years, our data illustrate sustained results, with more than 8% of students entering surgical residencies, significantly higher than the National Residency Match Program's average (p < 0.025). Surgical interest groups spark early and lasting interest in surgery that may influence residency decisions. Moreover, these programs can be successfully run entirely by preclinical students and implemented in other institutions.

Bulk liquid membrane extraction of silver(I) with 2-mercaptobenzothiazole as a carrier: Kinetic approach

The transport and separation of silver(I) ions across a bulk liquid membrane by 2-mercaptobenzothiazole (MBT) as carrier were investigated. The efficiency of Ag(I) transport was studied as a function of different parameters. The maximum of Ag(I) recovery was 85% in the presence of thiourea 0.1 M at pH 1, as complexing agent in the receiving phase, for a short extraction time of 4 h. A selective separation between Ag(I) and Mn(II) ions from equimolar mixture Ag–Cu–Mn solutions was performed. Besides, we have applied the kinetic model involving two consecutive irreversible first-order reactions to calculate the pseudo-first-order apparent membrane entrance and exit rate constants ke and ks, respectively. Under optimal conditions, the kinetic model curves of time dependence of silver concentrations (R) in the feed, membrane and receiving phases showed a good agreement with the experimental results. The apparent rate constants values were 6.93 × 10−3 min−1 for ke and 6.81 × 10−2 min−1 for ks. The transport of silver(I) is mainly controlled by the slow reaction of the formation of Ag–MBT complex at the membrane entrance.

Mathematical modeling of lymphocyte kinetics reveals true residence times in and preferential migration of lymphocytes via ovine lymph nodes (CAM4P.157)

Abstract There are many published values of lymphocyte residence times in lymph nodes of various mammals such as mice, rats, and sheep. Yet, most of these estimates have been obtained semiquantitatively, without the use of mathematical modeling, which raises a question about assumptions underlying such estimates. We developed a novel mathematical model for migration of lymphocytes in the whole body which takes into account the known biological details of how lymphocyte enter and exit major lymphoid tissues. We applied this novel mathematical model to experimental data on cannulation of different ovine lymph nodes (LNs). In particular, we predicted that in sheep, recirculatory lymphocytes spend on average 3 hours in the spleen and 20 hours in LNs with a distribution of residence times in LNs following a skewed gamma (lognormal-like) distribution. This is in contrast which a recent suggestion that the distribution of residence times of naïve T cells in murine LNs is exponential. We also found that lymphocytes isolated from the prescapular LN have a two-fold increased entrance rate into the prescapular LN as opposed to the intestinal LN. Importantly, the data could not be explained by preferential retention of cells in a specific LN. Taking together, our work illustrates the power of mathematical modeling in predicting the kinetics of lymphocyte migration in sheep and provides quantitative estimates of lymphocyte residence times in major ovine lymphoid tissues.

A Study on the Operation of a “Temporary Teacher Training Academy” in the 13 Provinces in the 1920s

As it approached the 1920s, the entrance rate to primary school rose among Korean people, which led to the multiplication of primary schools around the nation. Another consequence was the growing need for Korean elementary school teachers to teach Korean students, but the demand was not met because the teacher training institutions only educated Japanese teachers. Having the establishment of school of education in mind, the Japanese Government General of Korea opened a “Temporary Teacher Training Academy” in each province as a temporary measure. Each of the 13 provinces opened and ran such an academy at the seat of provincial government in April and May, 1920. The establishment of a temporary teacher training academy was a ground-breaking event in the modern history of teacher training. Such academies helped the teacher training system concentrated on Seoul and some large cities expand around the nation and further were inherited as schools of education, becoming a matrix for today’s elementary teacher training institutions.

Club convergence and factors of digital divide across countries

By examining the digital divide phenomenon among 108 countries, this paper attempts to develop a greater understanding of the factors that can foster a more creative global economy. As part of this investigation, a new ICT development index is constructed using principal component analysis and the inclusion of conventional ICT development indicators. Using Phillips and Sul's (2007) log t convergence test, we found that the level of digitalization convergence that exists among the 108 countries analyzed can be categorized into three different groupings. Within these groups, we found that the 1st group which contains the highest level of convergence showed the slowest speed of convergence, while the results for the 3rd group displayed the lowest convergence level with the highest speed of convergence among its members in digitalization. This study also identified the factors that drive a country's digitalization convergence level, these included: per capita GDP, tertiary education entrance rate, the ratio of urban population, and the share of service trade in GDP. With the exception of urban population, which showed results to the contrary, all of these factors were proven to raise a country's likelihood to belong to a higher convergence level. As for policy measures that can be used to foster a creative economy, marginal effect analysis identifies the tertiary education entrance rate as being the most effective means for raising the digitalization convergence level.

Theoretical analysis of selectivity mechanisms in molecular transport through channels and nanopores

Selectivity is one of the most fundamental concepts in natural sciences, and it is also critically important in various technological, industrial, and medical applications. Although there are many experimental methods that allow to separate molecules, frequently they are expensive and not efficient. Recently, a new method of separation of chemical mixtures based on utilization of channels and nanopores has been proposed and successfully tested in several systems. However, mechanisms of selectivity in the molecular transport during the translocation are still not well understood. Here, we develop a simple theoretical approach to explain the origin of selectivity in molecular fluxes through channels. Our method utilizes discrete-state stochastic models that take into account all relevant chemical transitions and can be solved analytically. More specifically, we analyze channels with one and two binding sites employed for separating mixtures of two types of molecules. The effects of the symmetry and the strength of the molecular-pore interactions are examined. It is found that for one-site binding channels, the differences in the strength of interactions for two species drive the separation. At the same time, in more realistic two-site systems, the symmetry of interaction potential becomes also important. The most efficient separation is predicted when the specific binding site is located near the entrance to the nanopore. In addition, the selectivity is higher for large entrance rates into the channel. It is also found that the molecular transport is more selective for repulsive interactions than for attractive interactions. The physical-chemical origin of the observed phenomena is discussed.

Balancing quality and quantity to build research universities in Taiwan

Higher education in Taiwan has expanded dramatically in the previous three decades. The number of students enrolled in higher education institutions has nearly quadrupled from 348,290 (1984) to 1,345,000 (2013). In 2012, the gross entrance rate of higher education reached 84.43 %, which is higher than most higher education systems in Asia. Higher education that transforms from a mass system to a universal system raises public concern regarding its quality. This study explored situations arising from a change to right-based higher education, particularly in pursuing a balance between quality and quantity in the process of establishing research universities. We selected two top public universities to illustrate how institutional arrangements play crucial roles in balancing quality and quantity. The findings reveal strong pressure for a world-class university within both universities, whereas student opinions reflect a neglect of instruction. In this case, faculty focused less attention on teaching compared to their research. These two universities should focus more efforts on teaching to balance quality and quantity toward a world-class research university.

Corner and sloped culvert baffles improve the upstream passage of adult European eels (Anguilla anguilla)

Installation of baffles intended to improve fish passage through culverts can reduce discharge capacity and trap debris, increasing flood risk. A sloping upstream face may reduce this risk, but new designs must be tested for fish passage efficiency. The European eel (Anguilla anguilla) is a critically endangered species, yet the suitability of even common baffle types to aid upstream movement has not been tested. This study compared the water depth, velocity, turbulent kinetic energy (TKE), and upstream passage performance of adult yellow-phase eels, between three 6m long culvert models: smooth and unmodified (control); containing corner baffles (treatment 1); and with prototype sloped baffles installed (treatment 2). Passage of individual fish was assessed during 25 one-hour trials per model. Performance was quantified as entrance efficiency, number of entries per fish, passage efficiency, and overall efficiency. Total and passage delay, and successful passage time were also evaluated. Despite some individuals being able to swim against unexpectedly high water velocities (>1.5ms−1 for 4m), passage performance in the control was poor, with an overall efficiency of 28%. Compared to the control, both treatments increased the mean centreline water depth by approximately 0.11m, created heterogeneous flow conditions with low velocity resting areas, and reduced maximum velocities. As a result, entrance rate and all efficiency parameters were higher for the treatments than for the control (overall efficiency=84%), despite longer passage delay. The TKE was slightly higher in treatment 2 than 1, but there was no difference in water depth or overall efficiency. The findings show that both corner and sloped baffles can mitigate for impeded upstream adult eel movement. The extent to which the sloping upstream face will improve debris transport should be explored further.

Population Attributable Fraction of Lower Education for Mortality in Korea with Improvement of Educational Attainment and No Improvement in Mortality Inequalities

Background Life expectancy in Korea increased from 52.4 in 1960 to 80.3 in 2009. This is 2.5 times as large as OECD countries' average increase for the same period. At the same time, Korean educational attainment has greatly increased. The high school (ISCED 3) entrance rate has risen to over 90% since the 1960s, The increase in educational attainment would be expected to decrease the magnitude of the population attributable fraction (PAF) of lower education for mortality in Korea. On the other hand, the increase …

경영학 수업에서 팀 프로젝트활동과 수업만족에 관한 연구

2010년도에 들어서면서 학령인구의 감소와 함께 고등학교 졸업생들의 대학진학률 하향추세로, 대학들은 학생 선발과 양질의 교육콘텐츠 제공이라는 2중의 어려움에 직면하고 있다. 이에 각 대학은 환경의 변화에 대한 신속한 대응과 동시에 다양하고 전문화된 대학교육서비스(팀기반 프로젝트학습, 사례연구, e-러닝, 액션러닝 등)를 도입하고 있다. 본 연구에서는 대학생을 대상으로 팀기반 프로젝트학습이 수업만족에 미치는 영향을 조사하고자 하였다. 이를 위한 측정항목으로 4개 요인(팀 응집력, 팀워크, 팀 성과 및 목표달성)을 설정하고, 설문조사(4개 과목, 34팀, 134명)를 통해서 자료를 수집하여, 구조방정식모형으로 분석했다. 연구모형검증 결과는 팀 응집력<TEX>${\rightarrow}$</TEX>팀워크<TEX>${\rightarrow}$</TEX>수업만족의 구조가 제시되었으며, 팀 성과와 목표달성은 수업만족에 미치는 영향이 유의하지 않은 것으로 나타났다. 팀기반 프로젝트학습의 경우 팀응집력이 높아야 수업만족정도가 높아지는 것으로 분석되었다. Since 2010, the universities in Korea have been faced severe difficulties on the selection of students and on the delivery of high quality education services, as the number of students is reduced and the college entrance rate is declined. To solve these problems, the universities have introduced the various and professional education services such as team-based projects, case study, e-learning, action learning, etc. The purpose of this study is to examine the effect of team-based project learning on the student's satisfaction in business education. The 4 factors(team cohesiveness, teamwork, team performance and goal achievement) are measured by using questionnaire survey and data are collected from 134 students(34 teams) for 4 subjects. The results show that the structure of team cohesiveness<TEX>${\rightarrow}$</TEX>teamwork<TEX>${\rightarrow}$</TEX>student's satisfaction is statistically significant, and that team performance and goal achievement are not significant. The student's satisfaction in team-based project learning would highly be related with team cohesiveness.

Kinetic of Alkaloids Extraction from Plant by Batch Pertraction in Rotating Discs Contactor

A liquid membrane process of Alkaloids extraction from Datura Innoxia solution was studied applying pertraction process in rotating discs contactor (RDC). Decane as a liquid membrane and dilute sulphuric acid as stripping solution were used. The effect of the fundamental parameters influencing the transport process, e.g. type of solvent used, effect of disks speed, amount of liquid membrane and effect of pH for feed and strip solution. The transport of alkaloids was analysed on the basis of kinetic laws of two consecutive irreversible first order reactions. Thus, the kinetic parameters (k1, k1, , tmax, and ) for the transport of alkaloids were determined. The effect of organic membrane type on percentage of Alkaloids transport was found to be in the order (n-decane&gt; n-heptane&gt; n-hexane&gt; ethyl ether). The results showed that the highest alkaloids extraction was obtained when using two stages, (10 rpm) discs speed, (pH=9.5) of feed solution and (pH=2) of acceptor solution in n-decane. Observation showed that the membrane entrance rate constant k1 and percentage of alkaloids transported in strip phase increased with increasing numbers of stages but the exit rate constant k2 decreased. The alkaloids extraction ratio increased with increasing the disks speed from 5 to 10 rpm but decreased at 15 rpm and decreased when increasing the volume of membrane. Also pH of feed and strip solution affected the extraction ratio and rate constants.

Mathematical modeling reveals kinetics of lymphocyte recirculation in the whole organism.

The kinetics of recirculation of naive lymphocytes in the body has important implications for the speed at which local infections are detected and controlled by immune responses. With a help of a novel mathematical model, we analyze experimental data on migration of 51Cr-labeled thoracic duct lymphocytes (TDLs) via major lymphoid and nonlymphoid tissues of rats in the absence of systemic antigenic stimulation. We show that at any point of time, 95% of lymphocytes in the blood travel via capillaries in the lung or sinusoids of the liver and only 5% migrate to secondary lymphoid tissues such as lymph nodes, Peyer's patches, or the spleen. Interestingly, our analysis suggests that lymphocytes travel via lung capillaries and liver sinusoids at an extremely rapid rate with the average residence time in these tissues being less than 1 minute. The model also predicts a relatively short average residence time of TDLs in the spleen (2.5 hours) and a longer average residence time of TDLs in major lymph nodes and Peyer's patches (10 hours). Surprisingly, we find that the average residence time of lymphocytes is similar in lymph nodes draining the skin (subcutaneous LNs) or the gut (mesenteric LNs) or in Peyer's patches. Applying our model to an additional dataset on lymphocyte migration via resting and antigen-stimulated lymph nodes we find that enlargement of antigen-stimulated lymph nodes occurs mainly due to increased entrance rate of TDLs into the nodes and not due to decreased exit rate as has been suggested in some studies. Taken together, our analysis for the first time provides a comprehensive, systems view of recirculation kinetics of thoracic duct lymphocytes in the whole organism.

Diffusion of Mixtures of Light Alkanes and Benzene in Nano-Sized H-ZSM5

The joint transport of linear C4–C6 alkanes and benzene has been studied over nanosized H-ZSM5 crystals by fast-time-resolved infrared spectroscopy. The internal and external concentration profiles during the coadsorption of alkanes and aromatics were directly monitored for a zeolite in which transport is controlled by the pore entrance step. The detailed kinetic analysis revealed a decrease in the adsorption and pore entrance rates of light hydrocarbon molecules upon addition of benzene by about 10–30%. This was caused by both a reduction in the rate constants and in the coverage at the external surface. On the other hand the apparent diffusion coefficient of benzene decreased up to 80% in comparison to the pure component. This decrease is attributed to a competitive adsorption at sites near the pore mouth. The extent increased with decreasing chain length of the cosorbed alkane, which corresponds to a simultaneous decrease in occupation of pore mouth sites by light hydrocarbons.

Rapid transfer of methyl red using calix[6]arene as a carrier in a bulk liquid membrane

Abstract In the present investigation, a calix[6]arene-based derivative ( 1 ) is employed as a selective carrier for the efficient transport of methyl red (MR) through bulk liquid membrane (BLM). Initially, the selectivity of 1 towards MR was confirmed among different dyes, such as methyl green (MG), methyl violate (MV), methylene blue (MB), methyl orange (MO), and eosin gelblich (EG) by liquid–liquid extraction experiments. Furthermore, the effect of the initial MR concentration of salts (NaCl, Na 2 SO 4 , and Na 2 CO 3 ) and of the pH of the acceptor phase were also optimized using liquid–liquid extraction. Afterwards, the influence of basic parameters, such as carrier concentration in membrane phase, type of solvent, and stirring rate on MR transport was determined through BLM. Mass transfer of MR through BLM was analyzed by following the kinetic laws of two consecutive irreversible first-order reactions, and the kinetic parameters ( k 1 , k 2 , R m max , t max , J d max , J a max ) were also calculated. Apparently, increase in membrane entrance ( k 1 ) and exit rate ( k 2 ) constants was accompanied by a rise in carrier concentration under a high stirring rate. In addition, CH 2 Cl 2 proved to be a better solvent than CHCl 3 and CCl 4 . The % transport of MR was 99% across the liquid membrane under optimized conditions. Real textile industrial wastewater samples gave also appreciable results in BLM under optimized conditions.

Do Greater School Autonomy and Accountability Make a Difference? Evidence from the Random Assignment of Students into Private and Public High Schools in Seoul

We study the effects of school autonomy using a randomized natural experiment in Seoul. Private and public schools subject to the equalization policy in Seoul admit students assigned randomly to them, receive equal government funding, charge identical fees, and use similar curricula, while private schools have greater flexibility in personnel decisions and their principals and teachers face stronger incentives to perform. We find that private high schools have fewer violent incidents per student, greater four-year college entrance rates, and better average students’ test scores. The effects appear to channel through the within-school dispersions of teacher salary and types.

Linear response in the nonequilibrium zero range process

We explore a number of explicit response formulæ around the boundary driven zero range process to changes in the exit and entrance rates. In such a nonequilibrium regime kinetic (and not only thermodynamic) aspects make a difference in the response. Apart from a number of formal approaches, we illustrate a general decomposition of the linear response into entropic and frenetic contributions, the latter being realized from changes in the dynamical activity at the boundaries. In particular in this way one obtains nonlinear modifications to the Green–Kubo relation. We end by bringing some general remarks about the situation where that nonequilibrium response remains given by the (equilibrium) Kubo formula such as for the density profile in the boundary driven Lorentz gas.